The present inventive concept relates to photolithography apparatus and, more particularly, to extreme ultraviolet light source devices which may be used in conjunction with photolithography apparatus and processes.
A photolithography process is used, for example, to form a semiconductor device on a wafer. In producing fine features on wafers, extreme ultraviolet light (EUV) is advantageously adopted as a light source in photolithography apparatus. The EUV can be generated by a laser-produced-plasma (LPP) apparatus and method disclosed in U.S. Publication No. 2011/0248191. However, with the use of this LPP apparatus, contamination of the collector mirror with target material or byproducts thereof is frequently observed. Therefore, there is a need to improve the LPP apparatus and method to reduce or prevent such contamination which impairs the efficiency and useful life of the apparatus.